1. 寬幅型鋼的輥式(shi)冷彎成(cheng)型的特點


  ①. 由于帶(dai)坯(pi)寬度(du)大、彎曲角多,因而需(xu)要的成型道次(ci)較(jiao)多(20~30)。


  ②. 在彎(wan)曲(qu)成型過程中(zhong),帶(dai)鋼的(de)(de)橫向相互牽(qian)拉作用大,因(yin)此,必須(xu)考慮(lv)帶(dai)鋼在成型過程中(zhong)的(de)(de)寬(kuan)度(du)伸長。


  ③. 由(you)于(yu)型鋼寬(kuan)度(du)較大(da),而(er)(er)橫(heng)(heng)向剛度(du)較小,因而(er)(er)極易出(chu)現橫(heng)(heng)向彎曲的缺陷。此外,由(you)于(yu)邊緣拉伸累積效(xiao)應顯著,很容易出(chu)現中(zhong)間鼓包(bao)或邊浪等缺陷。


  ④. 許多用(yong)于(yu)寬(kuan)幅型鋼生產的帶鋼表面質量(liang)(liang)較高,因此,對(dui)表面變形和表面質量(liang)(liang)提出了更(geng)嚴格(ge)的要求。


 在寬(kuan)幅型(xing)(xing)(xing)(xing)鋼的(de)(de)成型(xing)(xing)(xing)(xing)工藝中,成型(xing)(xing)(xing)(xing)次(ci)序和彎曲方(fang)法(fa)對產(chan)品的(de)(de)質量有突(tu)出的(de)(de)影響。除了普(pu)通的(de)(de)順(shun)序成型(xing)(xing)(xing)(xing)和同時成型(xing)(xing)(xing)(xing)次(ci)序外,對寬(kuan)幅型(xing)(xing)(xing)(xing)鋼還可采用(yong)特有的(de)(de)專用(yong)繳(jiao)壓(ya)整形成型(xing)(xing)(xing)(xing)次(ci)序。這(zhe)種(zhong)方(fang)法(fa)在每一(yi)道次(ci)時對波紋進行(xing)預(yu)彎,且(qie)使型(xing)(xing)(xing)(xing)材(cai)(cai)斷面(mian)的(de)(de)中性(xing)線(xian)與成品型(xing)(xing)(xing)(xing)材(cai)(cai)的(de)(de)中性(xing)線(xian)相重合。這(zhe)時型(xing)(xing)(xing)(xing)材(cai)(cai)上下所受(shou)的(de)(de)力(li)矩相平衡,型(xing)(xing)(xing)(xing)材(cai)(cai)不(bu)會(hui)發生縱彎。



2. 寬幅輥式冷彎型鋼的孔形系統


 寬幅型(xing)(xing)鋼的孔形(xing)系統,如圖5-6所示。采用何(he)種(zhong)孔形(xing)系統,取決于多種(zhong)因(yin)素(su)。首(shou)先(xian),孔形(xing)系統決定了產(chan)品質量(liang),同(tong)時直(zhi)接影(ying)響到成(cheng)型(xing)(xing)機架數、成(cheng)型(xing)(xing)輥結構(gou)、成(cheng)型(xing)(xing)輥壽(shou)命、成(cheng)型(xing)(xing)輥安裝調整、換輥時間、成(cheng)型(xing)(xing)速度、成(cheng)型(xing)(xing)機組生產(chan)率(lv)、生產(chan)成(cheng)本和(he)消耗(hao)等,因(yin)此(ci)從經濟角度看,最(zui)優(you)(you)化的孔形(xing)系統是達到優(you)(you)質、高產(chan)、低消耗(hao)這一最(zui)終(zhong)目標的重要保證。


圖 6.jpg


 寬幅(fu)輥式(shi)冷彎型鋼的孔形系統一般可分為三類。


 ①. 同時成(cheng)型孔(kong)形:即在斷面各部分同時成(cheng)型


    同時成型孔(kong)形(xing)系統應(ying)用很(hen)廣泛,同時成型孔(kong)形(xing)系統有(you)時用來生產一些(xie)表面要求高的(de)波紋(wen)板[見(jian)圖(tu)5-6(a)],這種(zhong)孔(kong)形(xing)系統的(de)不(bu)足之處是輥耗較其他系統高。


 ②. 連(lian)續成型(xing)孔(kong)形(順序成型(xing))


   即先中(zhong)間波(bo)(bo)成型(xing)(xing),后邊部波(bo)(bo)成型(xing)(xing),或先中(zhong)心部位(wei)成型(xing)(xing),后邊緣部位(wei)成型(xing)(xing),如(ru)圖(tu)5-6(b)、(c)所示。連(lian)續(xu)孔形(xing)(xing)(xing)系(xi)統(tong)在生(sheng)產(chan)具有(you)6個(ge)或6個(ge)以上(shang)彎折點的(de)波(bo)(bo)紋(wen)型(xing)(xing)鋼(gang)(gang)中(zhong)得到廣(guang)泛應(ying)用。連(lian)續(xu)孔形(xing)(xing)(xing)系(xi)統(tong)生(sheng)產(chan)碳(tan)素結構鋼(gang)(gang)和低合金(jin)鋼(gang)(gang)波(bo)(bo)紋(wen)板時,與其他孔形(xing)(xing)(xing)系(xi)統(tong)相比,具有(you)在相同質量指標的(de)情(qing)況下輥耗最低的(de)優(you)勢。


 ③. 專用成型孔形


  就(jiu)是(shi)為保證所生產(chan)出的(de)(de)(de)型鋼產(chan)品質量高(gao),而采用(yong)(yong)的(de)(de)(de)專用(yong)(yong)孔(kong)形(xing)系統,見(jian)圖5-6(c).通常(chang)專用(yong)(yong)孔(kong)形(xing)系統主要是(shi)用(yong)(yong)來(lai)加(jia)工生產(chan)寬幅波紋型鋼。該孔(kong)形(xing)系統在開始階段,先將帶鋼預彎曲(qu)出圓弧形(xing)波,然后(hou)再將圓弧形(xing)波壓制成(cheng)帶有直(zhi)邊的(de)(de)(de)梯形(xing)波。這種成(cheng)型方法能(neng)夠保證各過渡彎曲(qu)角處金屬減(jian)薄最小(xiao),從而提(ti)高(gao)了(le)產(chan)品的(de)(de)(de)力學性能(neng)。



3. 寬幅(fu)型鋼冷彎成(cheng)型工(gong)藝的幾點(dian)說明(ming)


 ①. 成型道次


  寬(kuan)幅型(xing)(xing)鋼需(xu)要較多的成(cheng)(cheng)型(xing)(xing)道次,在(zai)輥(gun)式(shi)冷彎(wan)(wan)成(cheng)(cheng)型(xing)(xing)過(guo)程(cheng)(cheng)中(zhong)(zhong)主要加(jia)工過(guo)程(cheng)(cheng)為彎(wan)(wan)曲(qu)變(bian)(bian)形(xing),除產(chan)品(pin)(pin)彎(wan)(wan)曲(qu)角局部有輕微減(jian)(jian)薄(bo)外(wai),變(bian)(bian)形(xing)材料的厚度在(zai)成(cheng)(cheng)型(xing)(xing)過(guo)程(cheng)(cheng)中(zhong)(zhong)假定保持不(bu)變(bian)(bian);在(zai)孔形(xing)設計(ji)時,要注意合理分配變(bian)(bian)形(xing)量(liang),尤(you)其(qi)是第(di)一(yi)道、后面幾道,變(bian)(bian)形(xing)量(liang)不(bu)易過(guo)大。另外(wai)可以(yi)采用(yong)預(yu)彎(wan)(wan)輥(gun),對型(xing)(xing)材進(jin)行(xing)預(yu)彎(wan)(wan),且使(shi)型(xing)(xing)材斷面的中(zhong)(zhong)性(xing)線(xian)與成(cheng)(cheng)品(pin)(pin)型(xing)(xing)材的中(zhong)(zhong)性(xing)線(xian)重合,使(shi)型(xing)(xing)材上下(xia)所受的力平衡,從而(er)避免(mian)縱(zong)向彎(wan)(wan)曲(qu)。在(zai)加(jia)工過(guo)程(cheng)(cheng)中(zhong)(zhong)發現縱(zong)向彎(wan)(wan)曲(qu),可根據實際(ji)情況增加(jia)一(yi)些(xie)成(cheng)(cheng)型(xing)(xing)輥(gun),尤(you)其(qi)注意后面幾道。其(qi)他如使(shi)用(yong)矯直(zhi)機(ji)進(jin)行(xing)矯直(zhi),變(bian)(bian)更機(ji)架間距,采用(yong)托輥(gun)調整各(ge)架次的軋輥(gun)間隙等措施(shi)均(jun)可減(jian)(jian)少(shao)或消除縱(zong)向彎(wan)(wan)曲(qu)。


②. 成型速度


  輥式冷彎(wan)速度的控(kong)制(zhi),成型輥壓力的調(diao)整(zheng)要合適,盡量減(jian)少反復(fu)冷彎(wan),并適當進行潤滑和冷卻,控(kong)制(zhi)彎(wan)曲半徑等(deng)方法,可進一(yi)步減(jian)少熱(re)應力裂紋(wen)的產生(sheng),也可以防止(zhi)彎(wan)曲疲勞裂紋(wen)的產生(sheng)。


  在實際生產應用過程中,不斷完善冷彎(wan)成型(xing)工(gong)藝(yi),確(que)保(bao)(bao)產品(pin)的(de)設(she)計質(zhi)量和加工(gong)質(zhi)量,可充分發揮鋼板的(de)綜(zong)合機械性(xing)能,保(bao)(bao)證冷彎(wan)型(xing)鋼的(de)整體加工(gong)質(zhi)量。


③. 合理設計孔形、合理設置成型(xing)輥間隙


  由于鋼板(ban)所形(xing)(xing)成(cheng)(cheng)的(de)(de)(de)型(xing)鋼具有很大(da)的(de)(de)(de)慣性(xing)矩和抗彎模量(liang),特(te)別是由于應用(yong)上的(de)(de)(de)要(yao)求(qiu)需要(yao)預(yu)沖孔(kong)后進(jin)行(xing)冷(leng)彎加(jia)工(gong)生(sheng)產的(de)(de)(de),會形(xing)(xing)成(cheng)(cheng)材(cai)(cai)料(liao)表(biao)面平(ping)整度和材(cai)(cai)料(liao)邊(bian)緣(yuan)尺寸上的(de)(de)(de)差(cha)異,因(yin)此要(yao)求(qiu)對(dui)該(gai)類鋼板(ban)的(de)(de)(de)冷(leng)彎孔(kong)形(xing)(xing)的(de)(de)(de)設(she)計中(zhong)需要(yao)多加(jia)側向定(ding)位裝置,合理(li)設(she)計孔(kong)形(xing)(xing)、合理(li)布置軋輥(gun)間隙等(deng),確保進(jin)人每(mei)道孔(kong)形(xing)(xing)的(de)(de)(de)材(cai)(cai)料(liao)不跑偏,并盡可能地(di)消除(chu)材(cai)(cai)料(liao)表(biao)面平(ping)整度和材(cai)(cai)料(liao)邊(bian)緣(yuan)尺寸上的(de)(de)(de)差(cha)異對(dui)后續冷(leng)彎成(cheng)(cheng)型(xing)形(xing)(xing)狀的(de)(de)(de)影響(xiang);另一個突(tu)出的(de)(de)(de)特(te)點為(wei):鋼板(ban)的(de)(de)(de)成(cheng)(cheng)型(xing)回彈現象(xiang)較(jiao)嚴重,回彈會導致(zhi)出現弧邊(bian),必(bi)須(xu)依靠(kao)過(guo)彎來修正(zheng),而且(qie)過(guo)彎角比(bi)較(jiao)難(nan)掌握,需在生(sheng)產調試(shi)過(guo)程中(zhong)進(jin)行(xing)調整修正(zheng)。